<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function f() {
            var v1 = document.getElementById("sx").value;
            var v2 = document.getElementById("sj").value;
            document.getElementById("tb").innerHTML += "<tr>\n" +
                "        <th>" + "<input  type='checkbox' onclick='dd(this)'/>" + "</th>\n" +
                "        <th>" + v1 + "</th>\n" +
                "        <th>" + v2 + "</th>\n" +
                "    </tr>"
        }

        function dd(x) {
            var tr = x.parentNode.parentNode;
            var th = tr.getElementsByTagName("th");
            var div = document.getElementById("div");
            for (var i = 1; i < th.length; i++) {
                div.innerHTML += th[i].innerHTML + " ";
            }
            div.innerHTML += "<br/>";
            var trs = document.getElementById("tb").getElementsByTagName("tr");
            for (var i = 1; i < trs.length; i++) {
                if (trs[i] === tr) {
                    trs[i].innerHTML = "";
                }
            }
        }
    </script>
</head>
<body>
事项: <input id="sx" type="text"/>
<br/>
时间: <input id="sj" type="text"/>
<br/>
<input type="button" value="添加" onclick="f()"/>
<br/>
<h4>备忘录</h4>
<table id="tb" border="1" cellpadding="0" cellspacing="0" width="30%">
    <tr>
        <th></th>
        <th>事项</th>
        <th>日期</th>
    </tr>
</table>
<h4>已完成</h4>
<div id="div">
</div>
</body>
</html>